Recent Posts

The reason I need to do it myself is that the phone jack of the mobile is 4 rather than 3, this is sth I remembered today. sth like this for the phone and headphones 3.5mm plugs: https://uk.farnell.com/w/c/connectors/audio-video-connectors-adapters/audio-video-connectors/prl/results?no-of-contacts=4contacts&st=phone%20jack I think I will use a DPDT switch, LA4145 audio amplifier which I knew since I was 14yrs old, and the mic line will connect directly from the phone input jack to the output jack, no need for switching the mic.. https://uk.farnell.com/search?st=TS5A22362

Come to think about it there are infact Audio IC solutions that may fir your need well also like LM4836 it only needs a single supply max 5.5 volt. It has all you need,like input mux, DC volume control and mute And it is also in a TSSOP Package. It also look like you can score some on say ebay A mechanical switch may be quite attractive if you only want a simple switch. But as you start to ad functions like mute and volume controll. The part cost start to add up. 2 or 3 pole double throw switches and dual logarithmic potentiometers are not free. For your question about the  resistance value of the volume control. You can use that headphones for portable meadia very often have an impedance of 32 ohm @1KHz. So I guess you can start testing with a pot in the Kohm range

hi
If you plan to use mechanical switch to choose between the inputs, put the volume control on the output, a 10k resistor will do, the wiper of the volume is the output, and either ends of the resisitor is the input, the other end is GND, but you have to use dual wiper volume control for stereo.

The last one is an excellent idea! As Sideshow Bob, mechanical appears to be the best solution. I would then do sth like this:
https://www.ebay.com/itm/Nobsound-Little-Bear-Mc102-Mini-2-1-In-1-2-Out-3-5Mm-Stereo-Audio-Switch-Audio/202772854481?hash=item2f363436d1:g:VX4AAOSwC4NdckOd any idea about the resistance value of the volume control?

https://www.ebay.com/itm/3-5mm-Stereo-audio-Switching-Board-socket-2-IN-1-OUT-1-IN-2-OUT-CA/253225299876?hash=item3af5676fa4:g:83EAAOSwGMNbpFzs

Very simple and inexpensive

There are bluetooth devices that can be paired with multiple audio sources and could be switched between on the fly by manipulating buttons on headset.
One of the first links from google search: https://www.businessinsider.com/plantronics-backbeat-500-bluetooth-headphone-review-2017-4

Mosfet ?

No matter how you do, you can't do anything delicate with linear Rail Shaft Rod bearings.
I recommend using Linear Guideway & Blocks.
Price difference is not much.
But it gives more precise results.

sample
https://www.banggood.com/SBR12-200mm-Linear-Rail-Shaft-Rod-with-2Pcs-SBR12UU-Blocks-Bearing-p-1194494.html?utm_source=google&utm_medium=cpc_ods&utm_content=aurogon&utm_campaign=aurogon-tools-sds-maxcov-feed-feed&ad_id=343417354738&gclid=CjwKCAjw5fzrBRASEiwAD2OSV7qNXmn9xFh01o9TMo1nOWhcnT06uDkObKwP7Eg9T1cndy6LQNndrxoCeUoQAvD_BwE&cur_warehouse=CN

I recommend using linear guide and rail.
sample
https://www.banggood.com/Machifit-HGR15-100-1200mm-Linear-Rail-Guide-with-HGH15CA-Linear-Rail-Guide-Slide-Block-CNC-Parts-p-1443398.html?rmmds=search&ID=534072&cur_warehouse=CN

I've taken your advice and upgrading to T20 Supported Linear rails. My next question is does anyone see a problem using T8 lead screws to pushi the X and Y aound? (Dual lead screws for Y, one per side) and 1 for the X?

As an after thought I guess I should state that I'm thinking of making the gantry move and making the bed stationary

you can use single cell switch using the 4016 in your situation need two and make XOR logic on command pins or, a simple R/C network can be put in place of the 20k pot to fade the audio

I think the 4016 has to high switch On-State Resistance to be used in a switch for headphones. I think even the 4066 may have to high switch On-State Resistance. So I am still in favor of a mechanical switch here.